The human rights watchdog Amnesty International says it has received credible information that soldiers in Fiji beat up a man after he sent a series of angry text messages to the Prime Minister Frank Bainimarama.It is urging the authorities in Fiji to investigate.Amnesty says the 60-year old man is in hospital recovering after four army officers turned up at his home outside Suva, dragged him to a nearby alleyway and assaulted him.It says earlier the same day he had an exchange of angry text messages with the Prime Minister, alleging his songs were used without permission during the election campaign.Amnesty says the case points to what it claims is a wider culture of violence among Fiji's security forces, which authorities have shown little interest in addressing.It says the incident comes just weeks after a robbery suspect Vilikesa Soko died in police custody shortly after his arrest in August 2014 and follows last year's surfacing of a video showing recaptured prisoners being tortured by men identified as members of the security forces.